In order to prevent global warming, etc., the importance of technology for reducing environmental burdens is increasing. Among such technologies, recovering and reusing waste heat, which is conventionally disposed of because of no use value, has attracted attention, one of which is an adsorption-type heat pump.
The adsorption-type heat pump converts thermal energy at temperatures of for example, 100° C. or less into low-temperature heat by utilizing the movement of latent heat produced when a refrigerant, such as water or methanol, is adsorbed by or desorbed from an adsorbent, such as silica gel or active carbon.
The adsorption-type heat pump has an adsorber having an adsorbent and is capable of switching between an adsorption process of causing an adsorbent to adsorb a refrigerant and a desorption process of desorbing a refrigerant from an adsorbent. Further, the adsorption-type heat pump includes a condenser which condenses a refrigerant desorbed from the adsorber and an evaporator which evaporates a refrigerant supplied from the condenser and supplies an evaporated refrigerant to the adsorber.
In the adsorption process, the refrigerant in the liquid phase evaporates within the evaporator, the refrigerant having changed into the gas phase moves into the adsorber and is adsorbed by the adsorbent. At this time, the refrigerant takes the heat of evaporation within the evaporator, and therefore, it is possible to remove low-temperature heat from the evaporator.
In the desorption processes, the refrigerant is desorbed from the adsorbent by heating the adsorbent having adsorbed the refrigerant and the desorbed refrigerant is cooled and condensed within the condenser. The refrigerant having changed into the liquid phase is supplied to the evaporator. High-temperature heat used in the desorption process may be as low as about 60° C. depending on the kind of adsorbent, and therefore, it is possible to utilize the thermal energy of waste heat at various low temperatures as a high-temperature heat source.
By repeating the adsorption process and the desorption process, it is possible to generate low-temperature heat from high-temperature heat.
In the adsorption-type heat pump described above, between the adsorber and the evaporator, a valve is arranged in a flow passage which causes the refrigerant in the gas phase to flow from the evaporator to the adsorber. Further, between the adsorber and the condenser, a valve is arranged in a flow passage which causes the refrigerant in the gas phase to flow from the adsorber to the condenser. These valves check the backflow of the refrigerant.
As such a valve, a seat valve having a valve body in the form of a seat is used. The valve body in the form of a seat is opened and closed by a pressure difference between the adsorber and the evaporator or by a pressure difference between the adsorber and the condenser, and therefore, the structure is simple and no additional driving force for opening and closing the valve body needs to be used.
[Patent Literature 1] Japanese Unexamined Patent Publication (Kokai) No. 9-152221
[Patent Literature 2] Japanese Unexamined Patent Publication (Kokai) No. 8-135524